Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Cost	$ 387,177	$ 198,918
Accumulated Amortization	124,982	98,962
Net Book Value	262,195	99,956
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	5,302	5,302
Accumulated Amortization	4,553	4,325
Net Book Value	749	977
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	88,921	44,829
Accumulated Amortization	36,222	28,934
Net Book Value	52,699	15,895
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	25,490	6,298
Accumulated Amortization	5,035	2,953
Net Book Value	20,455	3,345
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	267,225	142,489
Accumulated Amortization	79,002	62,750
Net Book Value	188,223	$ 79,739
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Cost	239
Accumulated Amortization	170
Net Book Value	$ 69